Modeled Thickness of the Grande Ronde Basalt Geomodel Unit (grthk_f)

Metadata Updated: November 12, 2020

The grthk_f grid represents the modeled thickness of the Gronde Ronde Basalt geomodel unit at a 500 foot resolution. It is one grid of a geomodel that consists of eleven grids and a spatial extent polygon shapefile. As part of a U.S. Geological Survey Groundwater Resources Program study, a three-dimensional geomodel was constructed for approximately 53,000 mi2 of the Columbia Plateau in Washington, Oregon, and Idaho. This geomodel was constructed to define the general aquifer system geometry for use in a regional numerical groundwater flow model. Simplifications and assumptions consistent with this ultimate goal and the uncertainty in the available data were made. The geomodel units consist of Miocene age Columbia River Basalt Group strata and younger alluvial overburden covering approximately 44,000 mi2. Data were compiled from numerous databases and detailed studies completed during the past three decades. These data include stratigraphic interpretations made on more than 13,000 wells and a contiguous compilation of surficial geology and structural features spanning the study area. These data were simplified and used to construct piecewise-smooth trend surfaces that represent upper and lower subsurface geomodel unit boundaries in this complex folded and faulted terrain. The smoothness of the surfaces implicitly represents uncertainty in prediction of each surface resulting from data gaps, errors in borehole interpretations, errors in mapped contact locations, and uncertainty in the shape of the paleo-surface upon which flood basalts were emplaced. Using a rule-based algorithm, surfaces were then recombined to construct a fully three-dimensional model with a 500-foot grid resolution that is consistent with the data and for which error estimates may be made. The modeling process yielded improved estimates of unit volumes, refinement of location of large structural features, and identification of features that may be important for ongoing groundwater studies.

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License: No license information was provided. If this work was prepared by an officer or employee of the United States government as part of that person's official duties it is considered a U.S. Government Work.

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Metadata Date August 13, 2014
Metadata Created Date November 12, 2020
Metadata Updated Date November 12, 2020
Reference Date(s) October 1, 2010 (publication)
Frequency Of Update notPlanned

Metadata Source

Harvested from DOI Open Data

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Illustration of dataset

Additional Metadata

Resource Type Dataset
Metadata Date August 13, 2014
Metadata Created Date November 12, 2020
Metadata Updated Date November 12, 2020
Reference Date(s) October 1, 2010 (publication)
Responsible Party U.S. Geological Survey (Point of Contact)
Contact Email
Access Constraints Use Constraints: The U.S. Geological Survey should be acknowledged as the data source in products derived from these data., Access Constraints: None
Bbox East Long -115.367389272
Bbox North Lat 48.419366654
Bbox South Lat 44.261075488
Bbox West Long -121.844957854
Coupled Resource
Frequency Of Update notPlanned
Graphic Preview Description Illustration of dataset
Graphic Preview File
Graphic Preview Type JPEG
Licence Although these data have been used by the U.S. Geological Survey, U.S. Department of the Interior, no warranty expressed or implied is made by the U.S. Geological Survey as to the accuracy of the data. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the U.S. Geological Survey in the use of these data, software, or related materials. The use of firm, trade, or brand names in this report is for identification purposes only and does not constitute endorsement by the U.S. Geological Survey. The names mentioned in this document may be trademarks or registered trademarks of their respective trademark owners.
Metadata Language
Metadata Type geospatial
Progress completed
Spatial Data Service Type
Spatial Reference System
Spatial Harvester True

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